Gastroesophageal reflux after peroral endoscopic myotomy

We read with great interest the study by Kumbhari et al. on gastroesophageal reflux (GER) after peroral endoscopic myotomy (POEM), and the accompanying editorial [1] [2]. We would like to thank the authors for raising an important issue, which has long-term implications (e. g. Barrett’s esophagus and adenocarcinoma) and the potential need for antireflux procedures post POEM.

The incidence of GER in the study was 58 %, which is high compared with previous studies, including one by our group [3]. As the authors point out, there is a possibility of selection bias, as postprocedure pH studies were conducted in only 282 of the 467 patients who underwent POEM, and the basis for performing pH studies at the participating centers was unclear. If GER symptoms triggered the pH studies, a selection bias with higher incidence of GER post POEM is possible.

Although data for hiatal hernia were evaluated, there is no mention of the number of cases of hiatal hernia that were present (if any), and this can have an impact on GER postprocedure.

We would further like to point out that the relationship between GER and achalasia is complex and not completely understood, thus making inferences of GER post POEM challenging.

Heartburn, which is a major symptom of GER, can be seen in up to 50 % of achalasia patients, and a large number of them are on proton pump inhibitor (PPI) therapy (in some studies 50 % of cases). Although this symptom, as well as abnormal acid exposure on pH studies in the distal esophagus, may be due to multiple causes (e. g. stasis, fermentation), the lower esophageal spincter pressure in patients with achalasia and heartburn symptoms is lower than in those without GER symptoms [4], and these patients may represent a different subset of achalasia patients who are more prone to post-POEM reflux. While “heartburn” may represent a sense of chest discomfort and not true reflux, documenting the prevalence of PPI use prior to POEM is important. In this study, PPI use served as a surrogate maker for GER postprocedure. In the absence of preprocedure PPI use data it is difficult to justify PPI use as a marker for GER. The study also includes patients who underwent prior treatment (e. g. Heller procedure, dilation, and botox injections). In a study of achalasia patients treated with dilation, one third were found to have reflux on pH study but with unresolved or recurrent symptoms [5]. Given the significant number of patients who had some form of therapy in this study, and in the absence of preprocedure pH studies, it is unclear how many patients were already experiencing reflux prior to the POEM procedure.

We also note that nearly a quarter of the study population (> 22 %) could not be classified using the Chicago classification (incidentally the population with the least amount of GER), raising concerns about the uniformity of the manometric studies across different centers. It is unclear whether this “unclassified” group in part included patients with nonachalasia esophageal motility disorders.

The Asian population in the study constituted about 10 % of the study population, and therefore a subanalysis of GER in this patient population would have been of particular interest to us.

Finally, we believe that identification and preservation of the sling fibers is an important step during myotomy, as this precaution may decrease the incidence of GER.

A prospective study with clearly documented PPI use, pre- and postprocedure pH monitoring, and attention to defining and preserving the sling fibers, may help in our understanding of post-POEM GER.

• References

• 1 Kumbhari V, Familiari P, Bjerregaard NC. et al. Gastroesophageal reflux after peroral endoscopic myotomy: a multicenter case-control study. Endoscopy 2017; 49: 634-642
• 2 Rösch T, Repici A, Boeckxstaens G. Will reflux kill POEM?. Endoscopy 2017; 49: 625-628
• 3 Shiwaku H, Inoue H, Sasaki T. et al. A prospective analysis of GERD after POEM on anterior myotomy. Surg Endosc 2016; 30: 2496-2504
• 4 Spechler SJ, Souza RF, Rosenberg SJ. et al. Heartburn in patients with achalasia. Gut 1995; 37: 305-308
• 5 Patti MG, Arcerito M, Tong J. et al. Importance of preoperative and postoperative pH monitoring in patients with esophageal achalasia. Gastrointest Surg 1997; 1: 505-510